Q. I would like to clarify the NFPA 99 requirements for zone valve box locations and an intervening wall between the zone valve and patient outlets per NFPA 99 (2015 Edition) (1). There seems to be a lot of confusion with this particular code section. Some design professionals believe that a door is part of the intervening wall. What if the door is left open? Is the door considered part of the intervening wall? Is it required to meet a particular fire rating as required in other NFPA documents? Are glass doors and/or glass walls considered an intervening wall? There are times when zone valves are located directly outside of Operating Rooms. Yet, if the OR door is open, there is a possibility that inlets/outlets could remain in the direct line of sight without an intervening wall. There are also times when an emergency room or patient recovery room area may utilize glass walls/doors. Any thoughts are helpful and appreciated.

A. The section on zone valves needs to be applied with all of the requirements in mind. Some of the requirements provide additional insight into acceptable locations for zone valve boxes. I tend to use the line of sight rule for the paragraph you referenced. But “seeing” the valves through doorway openings (normally open or closed) shouldn’t apply to this rule. Glass doors (commonly seen in ICU spaces) and “hard” partitions provide appropriate separation if the area with the outlets can be considered a “separate room” from the zone valve location. Most “fire doors” are also expected to close (if normally open) during a fire event.

The overall intent, in my view, is to locate zone valves in an area that will protect a “first responder” (not necessarily emergency personnel; could be a charge nurse as well) when operating the valves during a fire event. The other paragraphs that help designate acceptable areas are included below, which in some cases supersede the intervening wall requirement. If it’s not in a “corridor” as required or the zone valves are in a room with the outlets, the intervening wall requirement doesn’t really matter because the other requirements haven’t been met. In other words, the location has to meet all the different location requirements before considering the intervening wall. All station outlets/inlets shall be supplied through a zone valve as follows:
(1) The zone valve shall be placed such that a wall intervenes between the valve and outlets/inlets that it controls.
(2) The zone valve shall serve only outlets/inlets located on that same story.
(3) The zone valve shall not be located in a room with station outlets/inlets that it controls. Zone valves shall be readily operable from a standing position in the corridor on the same floor they serve.